1. Field of the Invention
This invention relates to an extension for adjustable legs used in stilts, benches and other similar devices.
2. Description of the Prior Art
A wide variety of devices have been designed for extending or diminishing lengths and heights of apparatus such as stilts and benches. As examples, several patents that have been issued in the past few decades follow:
Woodward et al., U.S. Pat. No. 5,368,126, issued on Nov. 29, 1994, patents an adjustable work platform that can be adjusted vertically and that has foldable leg assemblies. The adjustment of the height of the work platform is done by moving the leg assemblies, versus independent extensions for leg assemblies, upwards or downwards through slideable collars of the work platform and positioning a securing pin within the desired aperture in each leg assembly.
Miyamoto, U.S. Pat No. 4,776,545, issued on Oct. 11, 1988, patents a bisymmetric bench stand with two main legs and a pair of cross-linked flat bars. The top ends of the bench stand can be bolted to any of a series of bolt holes in the main legs. The bottom ends of the bench stand are bolted to the main legs. The middles of the flat bars are screwed together at a series of positions corresponding to the bolt holes on the main legs. Height-adjustable auxiliary legs are attached to the bottom of the main legs.
Masterson, U.S. Pat. No. 4,569,516, registered on Feb. 11, 1986, patents a vertically adjustable leg for stilts that comprises upper and lower complementarily vertically slideably interfitted struts. To permit the length of the assembled struts to be readily varied, a quick-action lock is interposed between the struts.
Presently, heights of stilts and similar workpieces are generally adjusted by using quick-action locks. A channel-shaped tube is usually slid within each adjustable leg of the workpiece. The adjustable leg has several pairs of vertically-spaced, horizontally-aligned holes, with each hole being designed to receive a stop peg. A compression spring is often interposed between the stop pegs within the tube to constantly bias the stop pegs outwardly. Each lock is provided with a finger grip. The finger grips are manually urged together to retract the stop pegs from within the pair of holes of the adjustable leg and, thus, to adjust the height of the workpiece by vertical sliding movement of the channel-shaped tube within the adjustable leg of the workpiece. Although the finger grips are designed to be operated manually, considerable manual force is needed to squeeze the finger grips in order to retract the stop pegs from within the pairs of holes of the adjustable leg.
Due to the exposure of the workpieces to foreign material, such as dust, that are present at construction sites, some parts of the lock tend to bind. Because of such tendency to bind, the stop pegs do not always securely lodge themselves within the pair of holes of the adjustable leg. The loose positioning of the stop pegs within the holes of the adjustable leg may cause sudden opening of the lock and result in the fall of the workman.
A need has arisen for a lightweight channel-shaped extension that serves as a secure and accident-free means for easily, quickly and manually adjusting heights of workpieces.